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J 25 2 BAENZIGER' FUSE PLUG Original Filed Feb. 23, 192"! /N vsnroe By Q5" MY or shatter when it blows out.

Reis'sued June 25,1929.

PATENT OFFICE.

LEONA D. nanuzmna, or Amne'ron, mssaomism'rs, assmuon roacun unaware mac'rnnmo 00.,

onnsnms.

or cnnnsm, massacnusn'r'rs, a conronarxon or mssa- :msn PLUG.

Original m5. ncense, and m 1, 1928, Serial No. 110,0, fled February as, we. Application in:

' Y reissue filed February 21, 1829. Serial lilo. 841,854.

.This invention relates to fuse plugs or those Which are so designed as to be threaded into sockets similar to those ordinarily employed to receive the bases of incandescent lamps. The object of my invention is the production of a glass top fuse plug which Glass for this purpose is much superior to mica which has been used commonly heretofore, not darken or become more or less opaque with lapse of time as does mica, nor does it vary in color or transparency so that the fusible element is easily visible therethrough. The detection of blown fusible elements is thus made very easy, which is not true of those heretofore commonly used. A glass top, however, is liable to be broken if the hot vaporized metal is permitted to impinge directly onits side walls when the fusible element blows, this not only permitting the immediate escape of the lot gases and metal vaporwith its attendant fire hazard, but also exposing sharp edges of glass at the plug socket, making removal of the blown fuse plug therefrom difficult and dangerous.

This invention is an improvement on the construction shown in my application Serial No. 78,988, filed January 2, 1926.

This inventionrelates to a construction by which the hot gas and molten metal produced when thefusible element blows out will be prevented from coming in suflicient contact with the walls of the glass to cause breaking or shattering thereof.

Reference will now be had to the drawing forming a part'of this application wherein there is illustrated a preferred embodiment of my invention, but it is to be understood that'lthe elements thereof may be varied or changed as to shape, size or form without departing from the spirit of the invention. Figure 1 is a vertical section through the center of the'fus'e plug.

Figure 2 is a view of the fuse plug with the metallic shell partly broken away to show certain parts. i

,10 designates a top member or body terial such as glass.

fuse plug having a hollow 11 of a transparent ma- .denture or'opening 1 2, The bottom part of the fuse plug 12 is made of porcelain with an will not break since it does The lower edge ofthe 'f-hollow top member has a rectangular'inannular shoulder 13 a ainst which the lower edge of the glass mem r 11 may engage and an annular extension 14 which projects within the glass top. The shoulder 13 carries an extension 15 which fits into the opening 12, thus preventing relative rotation between the base and top members when the are assembled. A metallic shell '20, pre erably of copper or brass, has threads which may be engaged externally with threads of the fuse plug receiving socket, and which engage internally with mating threaded portions externally of the top member 11. A sleeve 16 of electro-non-conductingmaterial and preferably heat insulating is positioned within the side portions of the top member 11 and outwardly of the annular extension 14.

r The fusible element 17 is connected to a conducting rivet or button 21 which extends through the base member 12' in the usual manner, forms a loop 18 visible through the closed end of the top member. 11 and" the major portion of which is spaced from the sleeve 16, and it follows along the inside of this sleeve 16 into and through the opening 12, and along a recess or groove 19 in the side glass so that when this element blows, the hot gases and molten metal are prevented from coming into direct contact with the sides of the glass, thus preventing shattering thereof. Having thus described my invention, what I claim is:

1. A fuse plug comprising a hollow glass body closed at one end, a fusible element therein visible through said closed end, and means to revent hot ases and molten metal from the using of sai element from coming in suflicient contact with the side walls of said glass body, comprisin a. sleeve of electronon-conducting material positioned within said glass body in contiguous relation with tact with the walls of said body comprising a 1 the side wall thereof and spaced from the sleeve of non-conducting material positioned major portion of the fusible element. Within said bodybetween the Walls thereof b 2. A fuse plug comprising a hollow transand the periphery of the projection of said 5 parent body, a fusible element therein, an plug in contiguous relation with the Walls of insulation plug closing the bottom of said said body. 7

body and having aflprojection extending In testimony whereof I have afiixed my therein, and means to prevent hot gases and signature. i

molten metal from coming in suflieient con- LEONARD BAENZIGER. 

